<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>05_DOM操作2</title>
</head>
<body>
<input type="text" id="i1">
<input type="text" id="i2">
<button onclick="f1()">按钮1</button>
<hr>
<h4>我是标题:<span id="ss"></span> </h4>
<button onclick="f2()">按钮2</button>
<script>
    function f1(){
        console.log(i1.value, typeof i1.value);
        let a = parseFloat(i1.value);
        console.log(a, typeof a);
    }
    function f2() {
        //let spanE = document.querySelector('span');
        //let spanE = document.querySelector('#ss');
        let spanE = document.getElementById('ss');
        console.log(spanE);
        ss.innerHTML = '你好';
    }
</script>
</body>
</html>